1. Field of the Invention
This invention relates to photography, and more particularly, it relates to the use of certain sulfam(na)phthaleins derived from perhalomethylcarbinol-substituted 1-naphthols as light-screening dyes in photographic products and processes.
2. Description of the Prior Art
It is well known to use light-screening dyes in photographic elements. Such a dye may be incorporated as a filter dye in a light-sensitive emulsion layer(s) or in a layer coated over one or more light-sensitive emulsion layers or between two differently color-sensitized emulsion layers to modify the light record in the emulsion layer or to control the spectral composition of light falling on the underlying light-sensitive layer, or it may be incorporated as an antihalation dye in a non-light-sensitive layer positioned on either side of a support carrying the light-sensitive layer(s).
It is also well known that photographic films, and especially multicolor films, may and generally do vary from lot to lot, notwithstanding efforts to "repeat" previous films. Manufacturers of multicolor photographic films have developed a number of procedures to minimize the effects upon the final multicolor image of unavoidable variations in the manufacturing operations. These variations are reflected primarily in shifts in color balance as reflected in mismatching of the D log E curves of the individual red, green and blue exposures. Equipment used to coat multicolor films is highly precise but variations between intended coverage of silver halide and/or the dye image-forming materials do occur. Repeat batches of silver halide emulsions may, and usually do, vary in their photographic response. Individual layers may be dried to slightly different degrees. Films are stored for a period of time after coating to allow the films to "age", so that changes in sensitometry following coating have an opportunity to reach a plateau prior to sale. If the film is designed to be developed by a photofinisher or in a darkroom, processing of the exposed multicolor film is controlled within very narrow limits, typically within plus or minus a half degree of a prescribed temperature, in order to minimize sensitometric variations from film to film. Where the multicolor film is of the negative type, an opportunity to adjust the sensitometry occurs in printing the desired final positive image, during which operation the printing exposure may be appropriately color filtered.
The basic sources of sensitometric variations noted above exist also in multicolor diffusion transfer films, with the added complication that once the film is shipped, the sensitometric properties are essentially fixed. The opportunity for adjustment provided in darkroom processing, practically speaking, is unavailable for users of self-developing films. While professional and advanced amateur photographers may be skillful enough to utilize color correction filters to at least partially "rebalance" the color balance, ordinary users of the film would only be confused by such additional operations.
Commonly, assigned copending U.S. Patent application Ser. No. 537,124 of Edwin H. Land filed Dec. 30, 1974 is concerned with modifying the sensitometric properties of multicolor diffusion transfer film units to achieve the requisite color correction. This is accomplished by including a layer of a color correction filter dye(s) and effecting photoexposure therethrough, the filter dye(s) subsequent to processing being so positioned as not to contribute dye density to the multicolor transfer image, or preferably, the filter dye(s) being capable of being bleached as a result of contact with the photographic processing composition. Because the sensitometry is modified after the photosensitive element has been coated but prior to packaging of the film, the user is unaware of, and not involved in, the corrective action.
The dyes employed for this and other light-screening purposes, in addition to having the requisite spectral absorption characteristics for their intended use, should be photochemically inert, that is, they should not have any adverse effect on the properties of the light-sensitive emulsion layer(s), and preferably, should be capable of being permanently decolorized so as not to leave stain in association with the final image of the processed photographic element. In photographic processes where the light-screening dye is removed by being dissolved in a processing solution, it is usually preferred that the dye also decolorize in order to avoid contamination of the processing solution and to prevent staining from residual dye in the processed film unit.
Though various classes of dyes have been proposed for use in antihalation, color correction and other filter layers, the dyes heretofore employed have not been altogether satisfactory. Some of the dyes tend to reduce sensitivity, fog or exert other adverse effect on the light-sensitive material. However, the major drawback of previously employed dyes is their tendency to impart stain to the final image due to incomplete decolorization or reversal of some of the decolorized form to the original colored form. For example, some classes of dyes rely on the presence of a reagent, such as, a sulfite for "bleaching", i.e., decolorization and unless the dyes are removed from the light-sensitive material during or after processing, their color may reappear with a reduction in sulfite concentration.
Commonly assigned copending U.S. Patent Application Ser. No. 836,006 of Stanley M. Bloom, Alan L. Borror and James W. Foley now U.S. Pat. No. 4,139,381 is directed to the use of certain 3,3-disubstituted sulfam(na)phthaleins as photographic optical filter agents and filter agent precursors. As described therein, one of the 3-substituents is a 4'-hydroxy-1'-phenyl moiety or a 4'-hydroxy-1'-naphthyl moiety, the other of the 3-substituents is a phenyl moiety or a naphthyl moiety, and the N atom of the sulfam(na)phthalein ring is substituted with a carbonyl moiety that undergoes an irreversible cleavage reaction in alkaline solution above a predetermined alkaline pH. These compounds are initially colorless, i.e., they do not absorb visible radiation intended to expose the photosensitive material but which, upon contact with an aqueous alkaline solution of base having an alkaline pH above a given value forms a colored compound capable of absorbing such radiation thereby preventing further exposure of said photosensitive material by ambient light, which colored compound after remaining in contact with said solution of base above said pH for a predetermined time forms a colorless compound as a result of the irreversible cleavage of the carbonyl moiety.
The present invention is concerned with certain sulfam(na)phthaleins derived from 2-perhalomethylcarbinol-substituted 1-naphthols which are initially colored and which find utility as photographic light-screening dyes that are free from the drawbacks associated with the dyes previously used for this purpose. The subject sulfam(na)phthalein light-screening dyes, which will be defined with greater particularity hereinafter, have a form which absorbs radiation in the visible range of 400 to 700 nm below a given alkaline pH and decolorize by undergoing an irreversible cleavage reaction with base at a pH above said alkaline pH to yield a colorless product. Because of their ability to decolorize completely and irreversibly in base above a predetermined pH without requiring a reagent, such as, a sulfite for the "bleaching" reaction and because the colorless product produced upon irreversible cleavage is inert to changes in pH, the compounds may be retained in the photographic light-sensitive element without the possibility of color reappearing in time. Besides being non-staining, the compounds are inert with respect to the light-sensitive material and thus, may be positioned in a layer adjacent to a silver halide emulsion layer or directly incorporated into an emulsion layer without having any adverse effect on the properties of the emulsion.